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Relational algebra has been a crucial foundation for relational database systems, and has played a large role in enabling their success. A corresponding XML algebra for XML query processing has been more elusive, due to the comparative complexity of XML, and its history. We argue that having a sound algebraic basis remains important nonetheless. In this paper, we show how the complexity of XML can be modeled effectively in a simple algebra, and how the conceptual clarity attained thereby can lead to significant benefits. [ABSTRACT FROM AUTHOR]

Event processing will play an increasingly important role in constructing distributed applications that can immediately react to critical events. In this paper we describe the CEDR language for expressing complex event queries that filter and correlate events to match specific patterns, and transform the relevant events into new composite events for the use of monitoring applications. Stream-based execution of these standing queries offers instant insight for users to see what is occurring in their systems and to take time-critical actions. [ABSTRACT FROM AUTHOR]

Interactive computer systems, that is, systems in which users cyclically interact by getting and providing information, have already a widespread and increasing use in all areas of our society. One characteristic of such systems is that the user behavior affects the system behavior and vice-versa. There is strong evidence that much of the user behavior is reactive, that is, the user reacts to the instantaneous conditions at the action time. This paper presents the reactivity concept and describes a framework to model it in interactive systems, in particular Internet-based systems. We analyze an online auction within the framework. Based on eBay data, we identify attributes that affect the winner bidders' behavior, such as the auction time to finish. This paper presents the first findings towards the formal description and understanding of reactivity patterns in an e-commerce application, which will be useful in improving the application and building novel mechanisms. [ABSTRACT FROM AUTHOR]

Prova is a language for rule-based Java scripting to support information integration and agent programming on the web. Prova integrates Java with derivation and reaction rules supporting message exchange with various comminication frameworks. Prova supports transparent access to databases, retrieval of URLs, access to web services, and querying of XML documents. We briefly illustrate Prova and show how to implement a distributed bioinformatics application, which includes access to an ontology stored in a database and to XML data for protein structures. Finally, we compare Prova to other event-condition-action rule systems. [ABSTRACT FROM AUTHOR]

We describe a generic ECA service for implementing behavior using heterogeneous languages in the Semantic Web. The module details and implements our recent work on an ontology and language concept for a modular approach to ECA rules in the Semantic Web. The ECA level provides generic functionality independent from the actual languages and semantics of event detection, queries, and actions. [ABSTRACT FROM AUTHOR]

In our previous research we have proposed a new high-level model for the specification of Web applications that takes into account the way in which users interact with the application in order to actively react and supply appropriate contents or gather profile data. In this context, we have realized a proper execution framework to develop ReActive Web applications specified by means of the novel modeling paradigm. In this paper we discuss an e-learning case study implemented using our framework and introduce the visual design tools we have extended and developed in order to support the development of ReActive Web applications. [ABSTRACT FROM AUTHOR]

While XQuery is becoming a standard, the W3C is currently discussing the features of an update language for XML, and its requirements. Therefore, time is ripe for designing and defining the language features and extensions that are usually needed when updates are supported: reaction policies to constraint violations, business rules, and more. In the past years, several languages have been proposed for updates as well as for triggers in XML, such as XUpdate and Active XQuery. In this paper, we propose a visual approach to the formulation of active rules building on XQBE, a graphical query language for XML data. Our approach is motivated by the need to provide unskilled users with the ability to express business rules in an intuitive fashion. Visual triggers are then translated into statements that can be interpreted by query engines. [ABSTRACT FROM AUTHOR]

The Semantic Web is based on XML and RDF as standards for exchanging and storing information on the World Wide Web. Event-Condition-Action rules are a possible candidate technology for distributed web-based applications that require timely notification and propagation of events and information between different sites. This paper discusses the provision of ECA rules for XML and RDF data, and highlights some of the challenges that arise. [ABSTRACT FROM AUTHOR]

Reactivity, the ability to detect and react to events, is an essential functionality in many information systems. In particular, Web systems such as online marketplaces, adaptive (e.g., recommender) systems, and Web services, react to events such as Web page updates or data posted to a server. This article investigates issues of relevance in designing high-level programming languages dedicated to reactivity on the Web. It presents twelve theses on features desirable for a language of reactive rules tuned to programming Web and Semantic Web applications. [ABSTRACT FROM AUTHOR]

Users without knowledge of schemas or structured query languages have difficulties in accessing information stored in databases. Commercial and research efforts have focused on keyword-based searches. Among them, précis queries generate entire multi-relation databases, which are logical subsets of existing ones, instead of individual relations. A logical database subset contains not only items directly related to the query selections but also items implicitly related to them in various ways. Existing approaches to précis query answering assume that a database is pre-annotated with a set of weights, and when a query is issued, an ad-hoc logical subset is constructed on the fly. This approach has several limitations, such as dependence on users for providing appropriate weights and constraints for answering précis queries, and difficulty to capture different query semantics and user preferences. In this paper, we propose a pattern-based approach to logical database subset generation. Patterns of logical subsets corresponding to different queries or user preferences may be recognized and stored in the system. Each time a user poses a question, the system searches in a repository of précis patterns to extract an appropriate one. Then, this is enriched with tuples extracted from the database, in order to produce the logical database subset. [ABSTRACT FROM AUTHOR]

Pattern Management Systems and Inductive Databases, are proposed as a new generation of general purpose databases with the aim to manage data mining patterns and work as knowledge bases in support to the deployment of the KDD process. One of the main problems to be solved is the integration between data and patterns and pattern maintenance when data update. Unfortunately, the heterogeneity of the patterns that represent the extracted knowledge and of the different conceptual tools used to find the patterns make difficult this integration in a unique framework. In this paper, we explore the feasibility of using XML as the unifying framework for inductive databases, and present a model, named XDM (XML for Data Mining). We will show the basic features of the model, such as the storage in the same database of both data and patterns. To store patterns, we consider determinant for their interpretation the storage of the pattern derivation process which is described by the concept of statement, based on data mining operators. Some of the statements are automatically generated by the system while maintaining consistence between source and derived data. Furthermore, we show how the use of XML namespaces allows the effective coexistence of different data mining operators and provides extensibility to new operators. Finally, we show that with the use of XML-Schema we are able to define the schema, the state and the integrity constraints of an inductive database. [ABSTRACT FROM AUTHOR]

Portal Catalogs is a popular means of searching for information on the Web. They provide querying and browsing capabilities on data organized in a hierarchy, on a category/subcategory basis. This paper presents mining techniques on user navigational patterns in the hierarchies of portal catalogs. Specifically, we study and implement navigation retrieval methods and clustering tasks based on navigational patterns. The above mining tasks are quite useful for portal administrators, since they can be used to observe users' behavior, extract personal preferences and re-organize the structure of the portal to satisfy better user needs and navigational habits. These mining tasks have been implemented in the NaviMoz, a prototype system for mining navigational patterns in portal catalogs. [ABSTRACT FROM AUTHOR]

Patterns are concise, but rich in semantic, representation of data. The approaches proposed in the literature and by commercial systems for pattern management usually deal with few types of knowledge artifacts and mainly concern pattern extraction issues. Little effort has been posed in designing an overall framework dedicated to the management of different types of patterns, possibly user-defined, in an homogeneous way. PSYCHO (Pattern based SYstem arCHitecture prOtotype) is a recently developed tool, built on top of Oracle technologies, for generating, representing, and manipulating heterogeneous patterns, possibly user-defined. The aim of this paper is to present the PSYCHO system, by discussing the underlying theory, the reference architecture, and providing concrete examples of its usage. [ABSTRACT FROM AUTHOR]

Recent research efforts in the fields of data stream processing and data stream management systems (DSMSs) show the increasing importance of processing data streams, e. g., in the e-science domain. Together with the advent of peer-to-peer (P2P) networks and grid computing, this leads to the necessity of developing new techniques for distributing and processing continuous queries over data streams in such networks. In this paper, we present a novel approach for optimizing the integration, distribution, and execution of newly registered continuous queries over data streams in grid-based P2P networks. We introduce Windowed XQuery (WXQuery), our XQuery-based subscription language for continuous queries over XML data streams supporting window-based operators. Concentrating on filtering and window-based aggregation, we present our stream sharing algorithms as well as experimental evaluation results from the astrophysics application domain to assess our approach. [ABSTRACT FROM AUTHOR]

Service discovery is an essential technique to provide applications with appropriate resources. However, user mobility and heterogeneous environments make the discovery of appropriate resources difficult. The execution environments will be rapidly changed, so developers cannot predict available resources exactly in design time. Thus, service discovery frameworks for pervasive computing must guarantee transparent development environments to application developers. In this paper, we introduce how to semantically describe and discover a variety of services in different environments. This approach helps applications to find appropriate services even though the required ones are not available or not found. For this, we propose a fine-grained effect ontology which is used to reasonably evaluate functional similarity among different services, and a policy-based query coordination which is used to dynamically apply different resource constraints according to human activities. Finally, we show with a feasible scenario how to find appropriate services in different environments. Our approach helps applications to seamlessly perform their tasks across a dynamic range of environments. [ABSTRACT FROM AUTHOR]

Inconsistent contexts are death-wounds which usually result in context-aware applications' incongruous behaviors and users' perplexed feelings, therefore the benefits of context-aware computing will become less believed. This problem occurs in most sensor based applications due to the intrinsic drawbacks of fallible physical sensors which can only detect some evidence of real world's situations rather than global views of them. In this paper, we extend ontology based context modeling approach with some descriptive information added to contexts, modify reasoners to support time information, bring in a context lifecycle management strategy, establish a context exploitation mechanism, and propose an inconsistency resolution algorithm, fostering timely, exact and conflict-free contexts. Besides, evaluations and a case study are carried out to attest our design principles. [ABSTRACT FROM AUTHOR]

The rise of the Internet has introduced dramatic changes in managing and sharing digital resources among widely dispersed groups. This paper presents a policy-driven access management approach for ad-hoc collaboration to enable secure information sharing in heterogeneous network environments. In particular, we attempt to incorporate the features of distributed role-based access control, delegation and dissemination control to meet the fundamental access control requirements associated with resource originators. These features are realized in a set of XACML-based Role-based Originator Authorization policies (ROA). We propose a security architecture, called ShareEnabler, to achieve effective authorization and enforcement mechanisms in the context of Peer-to-Peer (P2P) networking oriented file sharing. We briefly discuss our proof-of-concept prototype implementation based on an existing P2P file sharing toolkit developed by Lawrence Berkeley National Laboratory. [ABSTRACT FROM AUTHOR]

Scientific workflows facilitate automation, reuse, and reproducibility of scientific data management and analysis tasks. Scientific workflows are often modeled as dataflow networks, chaining together processing components (called actors) that query, transform, analyse, and visualize scientific datasets. Semantic annotations relate data and actor schemas with conceptual information from a shared ontology, to support scientific workflow design, discovery, reuse, and validation in the presence of thousands of potentially useful actors and datasets. However, the creation of semantic annotations is complex and time-consuming. We present a calculus and two inference algorithms to automatically propagate semantic annotations through workflow actors described by relational queries. Given an input annotation α and a query q, forward propagation computes an output annotation α′; conversely, backward propagation infers α from q and α′. [ABSTRACT FROM AUTHOR]

Regular path queries are the basic navigational component of virtually all the mechanisms for querying semistructured data commonly found in information integration applications, Web and communication networks, biological data management etc. We start by proposing weight-enhanced regular path queries with semantics that allow user-assigned preference (query) weights to be naturally combined with quantitative database link-information for driving the navigation. Motivated by the fact that the main applications of semistructured data involve distributed data sources, we focus next on the distributed evaluation of the weight-enhanced path queries. We present a distributed algorithm for evaluating our proposed queries in a multi-source setting. Our algorithm is general in the sense that it does not assume a known topology of the network and it can work using asynchronous communication. This algorithm can also be used to solve multi-source shortest path problems for which the full graph is not known in advance. To the best of our knowledge our algorithm is the first to address this problem in such a setting. [ABSTRACT FROM AUTHOR]

In recent times, the proliferation of spatial data on the Internet is beginning to allow a much larger audience to access and share data currently available in various Geographic Information Systems (GISs). Unfortunately, even if the user can potentially access a huge amount of data, often, she has not enough knowledge about the spatial domain she wants to query, resulting in a reduction of the quality of the query results. This aspect is even more relevant in integration architectures, where the user often specifies a global query over a global schema, without having knowledge about the specific local schemas over which the query has to be executed. In order to overcome such problem, a possible solution is to introduce some mechanism of query relaxation, by which approximated answers are returned to the user. In this paper, we consider the relaxation problem for spatial topological queries. In particular, we present some relaxed topological predicates and we show in which application contexts they can be significantly used. In order to make such predicates effectively usable, we discuss how GQuery, an XML-based spatial query language, can be extended to support similarity-based queries through the proposed operators. [ABSTRACT FROM AUTHOR]

Most of the recent work on adaptive processing and continuous querying of data streams assume that data objects come in the form of tuples, thus relying on the relational data model and traditional relational operators as basis for query processing techniques. Complex types of objects, such as multidimensional data sets or the vast amounts of raster image data continuously streaming down to Earth from satellites have not been considered. In this paper, we introduce a data and query model as a comprehensive and practically relevant basis for managing and querying streams of remotely-sensed geospatial image data. Borrowing basic concepts from Image Algebra, we detail a data model that reflects basic properties of such streams of imagery. We present a query model that includes stream restrictions, transforms, and compositions, and provides a sound basis for formulating expressive and practically relevant queries over streams of image data. Finally, we outline how the data and query model is currently realized in a data stream management system for geospatial image data that supports geographic applications. [ABSTRACT FROM AUTHOR]

This paper summarizes the situation about using XLink for connecting XML instances. We discuss applications where XLink functionality can be useful, and derive requirements how the basic XLink technology should be supported in these scenarios. We compare several proposals dealing with interlinked XML data with our dbxlink approach which is a minimal extension to XLink and XPath, and we show how its semantics can be added to arbitrary XPath-based query engines. [ABSTRACT FROM AUTHOR]

Database clusters provide a cost-effective solutionn for high performance query processing. By using either inter- or intra-query parallelism on replicated data, they can accelerate individual queries and increase throughput. However, there is no database cluster that combines inter- and intra-query parallelism while supporting intensive update transactions. C-JDBC is a successful database cluster that offers inter-query parallelism and controls database replica consistency but cannot accelerate individual heavy-weight queries, typical of OLAP. In this paper, we propose the Apuama Engine, which adds intra-query parallelism to C-JDBC. The result is an open-source package that supports both OLTP and OLAP applications. We validated Apuama on a 32-node cluster running OLAP queries of the TPC-H benchmark on top of PostgreSQL. Our tests show that the Apuama Engine yields super-linear speedup and scale-up in read-only environments. Furthermore, it yields excellent performance under data update operations. [ABSTRACT FROM AUTHOR]

One missing point in the current research about p2p XML databases is the definition of a proper query algebra that addresses p2p -specific issues, such as the dissemination and replication of data, the dynamic nature of the system, and the transient nature of data and replicas. This paper describes a query algebra for queries over XML p2p databases that provides explicit mechanisms for modeling data dissemination and replication constraints. [ABSTRACT FROM AUTHOR]

In this paper we propose the GEM Language (GEL), a SQL-like query language, which is able to extract information from semistructured temporal databases represented according to the Graphical sEmistructured teMporal (GEM) data model. [ABSTRACT FROM AUTHOR]

In this paper, we propose a domain-specific query language called NeuroQL for the neuroscience domain. NeuroQL is designed primarily for neuroinformatics database users and aims to enable users to directly interact with neuroscience databases in their professional concepts and terms with the help of a conceptual data model. NeuroQL is DBMS independent and can be translated into traditional query language such as SQL, OQL and XQuery. It integrates some object-oriented features, and supports neuron domain-specific data types and query operators, which can dynamically evolve when the underlying database schema evolves. [ABSTRACT FROM AUTHOR]

We describe the design and implementation of the linguistic query language DDDquery. This language aims at querying a large linguistic database storing a corpus of richly annotated historic German texts. We use a graph-based data model that supports multiple independent annotation layers on a shared text layer as well as alignments of text layers representing the same text or related texts (e.g., translations). The corpus is stored in an object-relational database system with a text retrieval extension. DDDquery is based on XPath to leverage the familiarity of many users with this language. It is translated to SQL in a two phase compilation with first order logic as an intermediate language. This approach effectively decouples the query language from the schema of the underlying corpus. We provide an overview of DDDquery, the underlying ODAG data model, its implementation as relational schema, the predicates of the intermediate language, and describe both phases of the translation process. [ABSTRACT FROM AUTHOR]

Adaptive query processors make decisions as to the most effective evaluation strategy for a query based on feedback received while the query is being evaluated. In essence, any of the decisions made by the optimizer (e.g., on operator order or on which operators to use) may be revisited in an adaptive query processor. This paper focuses on changes to physical operators (e.g., the specific join operators used, such as hash-join or merge-join) in pipelined query evaluators. In so doing, the paper characterizes the runtime properties of pipelined operators in a way that makes explicit when specific operators may be replaced, and that allows the validity of operator replacements to be proved. This is illustrated with reference to the substitution of join operators during their evaluation. [ABSTRACT FROM AUTHOR]

Federated information systems integrate various heterogeneous autonomic databases and information systems. Queries respect to the federation have to be translated into the local query language and must be transformed with respect to the local data model. This paper deals with the problem of a global query according to an object-relational federation service. This SQL query is to be translated into an equivalent XQuery expression, so that it can be processed by the corresponding XML component database system according to the local schema. [ABSTRACT FROM AUTHOR]

Ontologies, formal specifications of domains, have evolved in recent years as a leading tool in representing and interpreting Web data. The inherent heterogeneity of Web resources, the vast amount of information on the Web, and its non-specific nature requires a semantically rich tool for extracting the essence of Web source content. The OntoBuilder project [5] supports the extraction of ontologies from Web interfaces, ranging from simple Search Engine forms to multiple-pages, complex reservation systems. Ontologies from similar domains are then matched to identify ontology mappings. [ABSTRACT FROM AUTHOR]

This paper presents a new intelligent mediators configuration approach which exploits high expressive description logics to represent metadata, and reasoning tasks in order to build more flexible mediation systems. A user specifies a needs expression in terms of (i) an interesting view over a given application domain, (ii) sources preferences and (iii) architectural requirements. A well-adapted mediator, is automatically configured according to these needs through a reasoning-based configuration process. A configured mediator can therefore be adapted in order to build knowledge-based mediation systems with an arbitrary architecture. [ABSTRACT FROM AUTHOR]

Web ontology language OWL DL has two-valued model theory semantics so that ontologies expressed by it become trivial when contradictions occur. Based on classical description logic $\mathcal{SHOIN(D)}$, we propose the four-valued description logic $\mathcal{SHOIN(D)}{\it 4}$ which has the ability to reason with inconsistencies. By transformation technic, we convert the reasoning problems of $\mathcal{SHOIN(D)}{\it 4}$ to the counterparts of $\mathcal{SHOIN(D)}$. So $\mathcal{SHOIN(D)}{\it 4}$ provides us with an approach to deal with contradictions by classical reasoning mechanism. [ABSTRACT FROM AUTHOR]

ORM (Object-Role Modeling) is a rich and well-known conceptual modeling method. As ORM has a formal semantics, reasoning tasks such as satisfiability checking of an ORM schema naturally arise. Satisfiability checking allows a developer to automatically detect contradicting constraints. However, no complete satisfiability checker is known for ORM. In this paper, we revisit existing patterns from literature that indicate unsatisfiability of ORM schemes i.e., schemes that cannot be populated, and we propose refinements as well as additions for them. Although this does not yield a complete procedure - there may be ORM schemes passing the pattern checks while containing unsatisfiable roles - it yields an efficient and easy to implement detection mechanism (specially in interactive modeling tools) for the most common conceptual modeling mistakes. [ABSTRACT FROM AUTHOR]

A data stream management system executes a large number of continuous queries in parallel. As stream characteristics and query workload change over time, the plan initially installed for a continuous query may become inefficient. As a consequence, the query optimizer will re-optimize this plan based on the current statistics. The replacement of the running plan with a more efficient but semantically equivalent plan at runtime is called dynamic plan migration. In order to have a sound semantic foundation for query optimization, we investigate dynamic plan migration for snapshot-equivalent plans. We develop a general method for dynamic plan migration that treats the old and new plan as snapshot-equivalent black boxes. This enables the query optimizer to apply the conventional transformation rules during re-optimization. As a consequence, our approach supports the dynamic optimization of arbitrary continuous queries expressible in CQL, whereas existing solutions are limited in their scope. [ABSTRACT FROM AUTHOR]

This paper is a critical analysis of the concept of ontology thus as it is used in contemporary computing science. It identifies three main problems with such a concept, two of which are intrinsic to it and one of which is extrinsic, so to speak, being related to the use that of ontology is made in applications. The first problem with ontology is that the only accepted definition of its main artifact is teleological rather than structural as it would be proper in computing science. The second problem is that claiming that ontology is in any way a semantic discipline requires such a limited and outdated notion of semantic to be to all practical purposes useless. The third and final problem is that the limitations and misconceptions of ontology might make it a limiting factor, rather than a help, for many of the applications for which it is sought. The article concludes that a profound reconsideration of the relation between computers and semantics might be overdue. [ABSTRACT FROM AUTHOR]

Querying live media streams is a challenging problem that becomes an essential requirement in a growing number of applications. We address the problem of evaluating continuous queries on media streams produced by media sources such as webcams and microphones. The temporal attributes and the order of stream tuples play essential roles in live stream generation and query execution. Furthermore, the temporal constraints and query semantics of related streams provide additional query optimization opportunities. We investigate the modeling issues and introduce the query processing techniques of a live media stream management system (MedSMan), including media capturing, automatic feature generating, declaration and query languages, temporal stream operators and querying algorithms. A prototype is implemented and we present experimental results to show the performance of our prototype using various real-time media experiments. [ABSTRACT FROM AUTHOR]

Several query languages have been proposed for managing data streams in modern monitoring applications. Continuous queries expressed in these languages usually employ windowing constructs in order to extract finite portions of the potentially unbounded stream. Explicitly or not, window specifications rely on ordering. Usually, timestamps are attached to all tuples flowing into the system as a means to provide ordered access to data items. Several window types have been implemented in stream prototype systems, but a precise definition of their semantics is still lacking. In this paper, we describe a formal framework for expressing windows in continuous queries over data streams. After classifying windows according to their basic characteristics, we give algebraic expressions for the most significant window types commonly appearing in applications. As an essential step towards a stream algebra, we then propose formal definitions for the windowed analogs of typical relational operators, such as join, union or aggregation, and we identify several properties useful to query optimization. [ABSTRACT FROM AUTHOR]

In autonomous distributed healthcare environments, patients' electronic medical records are controlled and managed by each healthcare facility. It is important to ensure that when records are accessed and transferred that it is done securely, while still respecting patients' rights on privacy and confidentiality of their personal health information. We propose a new tag-based data model for representing patients' electronic medical records as well as access and transfer policy statements. This model helps to categorize the patient information, as well as expressing patients' consent for a variety of domains (individual, health care provider and facility). Unlike most existing data models used in healthcare information systems, our model supports patients' consent expression in terms of healthcare facilities, healthcare providers, their roles, and categories of medical records or any combination of them within a single framework. Our model has been demonstrated by developing a prototype system using some trusted computing components. [ABSTRACT FROM AUTHOR]

Data management in medicine usually takes place through the usage of heterogeneous and legacy systems. So far, these information systems were rarely reusable into other investigations and, expecially in multicenter studies, their development absorbed part of the given funding. To overcome these limitation, we developed the EPIweb system, i.e. a totally configurable web-based information system which helps the epidemiologists/public health practitioners to conduct their (distributed) researches by following a workflow made up of the selection of the remote centers, the creation of the questionnaires, the data entry, the statistical processing of the data, and the generation of the technical reports. The most important EPIweb features are shown in the paper by means of a recent investigation conducted with the system. Finally, we discuss some open issues regarding the improvement of the EPIweb system in the direction of scientific workflow management. [ABSTRACT FROM AUTHOR]

We present a patient-oriented computer-based medical system which proposes advices on mild clinical signs treatment and medication. Therefore, this system can be considered a self-medication assistant tool. In a nutshell, this web application validates drug consumptions of a given patient, based on patient information stored in an electronic health care record, with a drug and symptom knowledge base. The efficiency and accuracy of the knowledge base inferences depend on the quality, quantity and recency of the drug instances. A practical source for these information are databases. Thus we developed a data integration solution which enables the mapping of relational databases to a Description Logics knowledge base. [ABSTRACT FROM AUTHOR]

To investigate molecular-biological causes and effects of diseases and their therapies it becomes increasingly important to combine data from clinical trials with high volumes of experimental genetic data and annotations. We present our approach to integrate such data for two large collaborative cancer research studies in Germany. Our platform interconnects a commercial study management system (eRN) with a data warehouse-based gene expression analysis system (GeWare). We utilize a generic approach to import different anonymized pathological and patient-related annotations into the warehouse. The platform also integrates different forms of experimental data and public molecular-biological annotation data and thus supports a wide range of genetic analyses for both clinical and non-clinical parameters. [ABSTRACT FROM AUTHOR]

Current methods for data integration are as difficult to use as they are powerful. Motivated by our work with clinical data and the people who analyze it, we present two components that allow non-technical users that are domain experts to create and reuse complex data integration processes. The GUAVA (GUI As View Apparatus) component enables data analysts to make informed data integration decisions based on detailed accounts of the user interface that was used to generate the data. The MultiClass component allows analysts to revisit decisions made for prior studies and reuse them or not each time the data is used. We describe these two components with examples where a warehouse of clinical data is used to support research studies. We describe the state of our implementation and why we believe the two components can be automatically translated into ETL workflows. [ABSTRACT FROM AUTHOR]

In this paper we propose an approach to manage in a correct way valid time semantics for semistructured temporal clinical information. In particular, we use a graph-based data model to represent radiological clinical data, focusing on the patient model of the well known DICOM standard, and define the set of (graphical) constraints needed to guarantee that the history of the given application domain is consistent. [ABSTRACT FROM AUTHOR]

Recent approaches in the research on inconsistent databases have started analyzing the first-order reducibility of consistent query answering, i.e., the possibility of identifying classes of queries whose consistent answers can be obtained by a first-order (FOL) rewriting of the query, which in turn can be easily formulated in SQL and directly evaluated through any relational DBMS. So far, the investigations in this direction have only concerned subsets of conjunctive queries over databases with key dependencies. In this paper we extend the study of first-order reducibility of consistent query answering under key dependencies to more expressive queries, in particular to unions of conjunctive queries. More specifically: (i) we analyze the applicability of known FOL-rewriting techniques for conjunctive queries in the case of unions of conjunctive queries. It turns out that such techniques are applicable only to a very restricted class of unions of conjunctive queries; (ii) to overcome the above limitations, we define a new rewriting method which is specifically tailored for unions of conjunctive queries. The method can be applied only to unions of conjunctive queries that satisfy an acyclicity condition on unions of conjunctive queries. [ABSTRACT FROM AUTHOR]

For several reasons a database may not satisfy a given set of integrity constraints (ICs), but most likely most of the information in it is still consistent with those ICs; and could be retrieved when queries are answered. Consistent answers to queries wrt a set of ICs have been characterized as answers that can be obtained from every possible minimally repaired consistent version of the original database. In this paper we consider databases that contain null values and are also repaired, if necessary, using null values. For this purpose, we propose first a precise semantics for IC satisfaction in a database with null values that is compatible with the way null values are treated in commercial database management systems. Next, a precise notion of repair is introduced that privileges the introduction of null values when repairing foreign key constraints, in such a way that these new values do not create an infinite cycle of new inconsistencies. Finally, we analyze how to specify this kind of repairs of a database that contains null values using disjunctive logic programs with stable model semantics. [ABSTRACT FROM AUTHOR]

One of the goals of cleaning an inconsistent database is to remove conflicts between tuples. Typically, the user specifies how the conflicts should be resolved. Sometimes this specification is incomplete, and the cleaned database may still be inconsistent. At the same time, data cleaning is a rather drastic approach to conflict resolution: It removes tuples from the database, which may lead to information loss and inaccurate query answers. We investigate an approach which constitutes an alternative to data cleaning. The approach incorporates preference-driven conflict resolution into query answering. The database is not changed. These goals are achieved by augmenting the framework of consistent query answers through various notions of preferred repair. We axiomatize desirable properties of preferred repair families and propose different notions of repair optimality. Finally, we investigate the computational complexity implications of introducing preferences into the computation of consistent query answers. [ABSTRACT FROM AUTHOR]

An architecture is proposed providing robust data acquisition facilities from input documents containing tabular data. This architecture is based on a data-repairing framework exploiting integrity constraints defined on the input data to support the detection and the repair of inconsistencies in the data arising from errors occurring in the acquisition phase. In particular, a specific but expressive form of integrity constraints (steady aggregate constraints) is defined which enables the computation of a repair to be expressed as a mixed integer linear programming problem. [ABSTRACT FROM AUTHOR]

We discuss, compare and relate some old and some new models for incomplete and probabilistic databases. We characterize the expressive power of c-tables over infinite domains and we introduce a new kind of result, algebraic completion, for studying less expressive models. By viewing probabilistic models as incompleteness models with additional probability information, we define completeness and closure under query languages of general probabilistic database models and we introduce a new such model, probabilistic c-tables, that is shown to be complete and closed under the relational algebra. [ABSTRACT FROM AUTHOR]

Executable schema mappings between XML schemas are essential to support numerous data management tasks such as data exchange, data integration and schema evolution. The novelty of this paper consists in a method for automatic generation of automappings (automorphisms) from key constraints and value dependencies over XML schemas, and designing algebraic operations on mappings and schemas represented by automappings. During execution of mappings some missing or incomplete data may be inferred. A well-defined executable semantics for mappings and operations on mappings are proposed. A mapping language XDMap to specify XML schema mappings is discussed. The language allows to specify executable mappings that can be used to compute target instances from source instances preserving key constraints and value dependencies. The significance of mappings and operators over mappings is discussed on a scenario of data exchange in a P2P setting. [ABSTRACT FROM AUTHOR]

Since XML is used as a storage format in an increasing number of applications, security has become an important issue in XML databases. One aspect of security is restricting access to data by certain users. This can, for example, be achieved by means of access rules or XML security views, which define projections over XML documents. The usage of security views avoids information leakage that may occur when we use certain access rules. XML views can be implemented by materialized views, but materialization and maintenance of views may cause considerable overhead. Therefore, we study translations from queries on views to equivalent queries on the original XML documents, assuming both the security views and the queries are specified by XPath expressions. Especially, we investigate which XPath fragments are closed under the composition of a view and a query. [ABSTRACT FROM AUTHOR]